Interaction of a colloidal sphere near a flat boundary

A colloidal sphere's diffusion is hindered near a surface due to hydrodynamic interactions . We study the hindered diffusion of a colloidal sphere near a glass surface using Digital Holographic Microscopy (DHM). Analysis of in-line holographic images of a diffusing colloidal sphere provides its three dimensional positions with nanometer resolution. We propose a general technique to determine the forces acting on the colloidal sphere near a flat boundary using Kernel Density Estimates (KDE), as a function of distance from the boundary. The results will help in understanding interactions between micron-sized colloidal particles near a boundary.